/*
 * PrimitiveScanner.java July 2006
 *
 * Copyright (C) 2006, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.core;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import wx.xml.simpleframework.xml.Order;
import wx.xml.simpleframework.xml.Version;

/**
 * The <code>PrimitiveScanner</code> performs the reflective inspection
 * of a class and builds a map of attributes and elements for each
 * annotated field. This acts as a cachable container for reflection
 * locations performed on a specific type. When scanning the provided
 * class this inserts the scanned field as a <code>Label</code> in to
 * a map so that it can be retrieved by name. Annotations classified
 * as attributes have the <code>Attribute</code> annotation, all other
 * annotated fields are stored as elements.
 *
 * @author Niall Gallagher
 * @see wx.xml.simpleframework.xml.core.Schema
 */
class PrimitiveScanner implements Scanner {

    /**
     * This is an empty section that is used by every scanner object.
     */
    private final Section section;

    /**
     * This contains the details for the class that is being scanned.
     */
    private final Detail detail;

    /**
     * Constructor for the <code>PrimitiveScanner</code> object. This
     * is used to represent primitives or other types that do not have
     * and XML annotations present.
     *
     * @param detail this contains the details for the class scanned
     */
    public PrimitiveScanner(Detail detail) {
        this.section = new EmptySection(this);
        this.detail = detail;
    }

    /**
     * This is used to acquire the default signature for the class.
     * The default signature is the signature for the no argument
     * constructor for the type. If there is no default constructor
     * for the type then this will return null.
     *
     * @return this returns the default signature if it exists
     */
    public Signature getSignature() {
        return null;
    }

    /**
     * This returns the signatures for the type. All constructors are
     * represented as a signature and returned. More signatures than
     * constructors will be returned if a constructor is annotated
     * with a union annotation.
     *
     * @return this returns the list of signatures for the type
     */
    public List<Signature> getSignatures() {
        return new LinkedList<Signature>();
    }

    /**
     * This returns a map of all parameters that exist. This is used
     * to validate all the parameters against the field and method
     * annotations that exist within the class.
     *
     * @return this returns a map of all parameters within the type
     */
    public ParameterMap getParameters() {
        return new ParameterMap();
    }

    /**
     * This is used to acquire the instantiator for the type. This is
     * used to create object instances based on the constructors that
     * have been annotated. If no constructors have been annotated
     * then this can be used to create default no argument instances.
     *
     * @return this instantiator responsible for creating instances
     */
    public Instantiator getInstantiator() {
        return null;
    }

    /**
     * This is used to acquire the type that this scanner scans for
     * annotations to be used in a schema. Exposing the class that
     * this represents allows the schema it creates to be known.
     *
     * @return this is the type that this creator will represent
     */
    public Class getType() {
        return detail.getType();
    }

    /**
     * This is used to acquire the <code>Decorator</code> for this.
     * A decorator is an object that adds various details to the
     * node without changing the overall structure of the node. For
     * example comments and namespaces can be added to the node with
     * a decorator as they do not affect the deserialization.
     *
     * @return this returns the decorator associated with this
     */
    public Decorator getDecorator() {
        return null;
    }

    /**
     * This method is used to return the <code>Caller</code> for this
     * class. The caller is a means to deliver invocations to the
     * object for the persister callback methods. It aggregates all of
     * the persister callback methods in to a single object.
     *
     * @return this returns a caller used for delivering callbacks
     */
    public Caller getCaller(Context context) {
        return new Caller(this, context);
    }

    /**
     * This is used to create a <code>Section</code> given the context
     * used for serialization. A section is an XML structure that
     * contains all the elements and attributes defined for the class.
     * Each section is a tree like structure defining exactly where
     * each attribute an element is located within the source XML.
     *
     * @return this will return a section for serialization
     */
    public Section getSection() {
        return section;
    }

    /**
     * This is the <code>Version</code> for the scanned class. It
     * allows the deserialization process to be configured such that
     * if the version is different from the schema class none of
     * the fields and methods are required and unmatched elements
     * and attributes will be ignored.
     *
     * @return this returns the version of the class that is scanned
     */
    public Version getRevision() {
        return null;
    }

    /**
     * This is used to acquire the <code>Order</code> annotation for
     * the class schema. The order annotation defines the order that
     * the elements and attributes should appear within the document.
     * Providing order in this manner makes the resulting XML more
     * predictable. If no order is provided, appearance is random.
     *
     * @return this returns the order, if any, defined for the class
     */
    public Order getOrder() {
        return null;
    }

    /**
     * This returns the <code>Label</code> that represents the version
     * annotation for the scanned class. Only a single version can
     * exist within the class if more than one exists an exception is
     * thrown. This will read only floating point types such as double.
     *
     * @return this returns the label used for reading the version
     */
    public Label getVersion() {
        return null;
    }

    /**
     * This returns the <code>Label</code> that represents the text
     * annotation for the scanned class. Only a single text annotation
     * can be used per class, so this returns only a single label
     * rather than a <code>LabelMap</code> object. Also if this is
     * not null then the elements label map must be empty.
     *
     * @return this returns the text label for the scanned class
     */
    public Label getText() {
        return null;
    }

    /**
     * This returns the name of the class processed by this scanner.
     * The name is either the name as specified in the last found
     * <code>Root</code> annotation, or if a name was not specified
     * within the discovered root then the Java Bean class name of
     * the last class annotated with a root annotation.
     *
     * @return this returns the name of the object being scanned
     */
    public String getName() {
        return null;
    }

    /**
     * This method is used to retrieve the schema class commit method
     * during the deserialization process. The commit method must be
     * marked with the <code>Commit</code> annotation so that when the
     * object is deserialized the persister has a chance to invoke the
     * method so that the object can build further data structures.
     *
     * @return this returns the commit method for the schema class
     */
    public Function getCommit() {
        return null;
    }

    /**
     * This method is used to retrieve the schema class validation
     * method during the deserialization process. The validation method
     * must be marked with the <code>Validate</code> annotation so that
     * when the object is deserialized the persister has a chance to
     * invoke that method so that object can validate its field values.
     *
     * @return this returns the validate method for the schema class
     */
    public Function getValidate() {
        return null;
    }

    /**
     * This method is used to retrieve the schema class persistence
     * method. This is invoked during the serialization process to
     * get the object a chance to perform an nessecary preparation
     * before the serialization of the object proceeds. The persist
     * method must be marked with the <code>Persist</code> annotation.
     *
     * @return this returns the persist method for the schema class
     */
    public Function getPersist() {
        return null;
    }

    /**
     * This method is used to retrieve the schema class completion
     * method. This is invoked after the serialization process has
     * completed and gives the object a chance to restore its state
     * if the persist method required some alteration or locking.
     * This is marked with the <code>Complete</code> annotation.
     *
     * @return returns the complete method for the schema class
     */
    public Function getComplete() {
        return null;
    }

    /**
     * This method is used to retrieve the schema class replacement
     * method. The replacement method is used to substitute an object
     * that has been deserialized with another object. This allows
     * a seamless delegation mechanism to be implemented. This is
     * marked with the <code>Replace</code> annotation.
     *
     * @return returns the replace method for the schema class
     */
    public Function getReplace() {
        return null;
    }

    /**
     * This method is used to retrieve the schema class replacement
     * method. The replacement method is used to substitute an object
     * that has been deserialized with another object. This allows
     * a seamless delegation mechanism to be implemented. This is
     * marked with the <code>Replace</code> annotation.
     *
     * @return returns the replace method for the schema class
     */
    public Function getResolve() {
        return null;
    }

    /**
     * This is used to determine whether the scanned class represents
     * a primitive type. A primitive type is a type that contains no
     * XML annotations and so cannot be serialized with an XML form.
     * Instead primitives a serialized using transformations.
     *
     * @return this returns true if no XML annotations were found
     */
    public boolean isPrimitive() {
        return true;
    }

    /**
     * This is used to determine whether the scanned class represents
     * a primitive type. A primitive type is a type that contains no
     * XML annotations and so cannot be serialized with an XML form.
     * Instead primitives a serialized using transformations.
     *
     * @return this returns true if no XML annotations were found
     */
    public boolean isEmpty() {
        return true;
    }

    /**
     * This method is used to determine whether strict mappings are
     * required. Strict mapping means that all labels in the class
     * schema must match the XML elements and attributes in the
     * source XML document. When strict mapping is disabled, then
     * XML elements and attributes that do not exist in the schema
     * class will be ignored without breaking the parser.
     *
     * @return true if strict parsing is enabled, false otherwise
     */
    public boolean isStrict() {
        return true;
    }

    /**
     * The <code>EmptySection</code> object creates a section for
     * used with primitives that has no values. No primitive can have
     * annotations as they will be processed by a transform rather
     * than by a schema object, this object saves memory and time.
     *
     * @author Niall Gallagher
     */
    private static class EmptySection implements Section {

        /**
         * This is an empty list used to create empty iterators.
         */
        private final List<String> list;

        /**
         * This is the source scanner object this is created for.
         */
        private final Scanner scanner;

        /**
         * Constructor for the <code>EmptySection</code> object. This
         * is used to represent a primitive where thare are no other
         * parts to the object. This acts as a lightweight container.
         *
         * @param scanner this is the owning scanner for the section
         */
        public EmptySection(Scanner scanner) {
            this.list = new LinkedList<String>();
            this.scanner = scanner;
        }

        /**
         * This will produce an interator with no elements. No elements
         * are returned because this represents an empty section. A
         * non-null value is best as it avoids possible exceptions.
         *
         * @return this returns an empty iterator for the section
         */
        public Iterator<String> iterator() {
            return list.iterator();
        }

        /**
         * This is used to return the name of the section. The name is
         * must be a valid XML element name. It is used when a style
         * is applied to a path as the section name must be styled.
         *
         * @return this returns the name of this section instance
         */
        public String getName() {
            return null;
        }

        /**
         * This is used to acquire the path prefix for the section. The
         * path prefix is used when the section is transformed in to an
         * XML structure. This ensures that the XML element created to
         * represent the section contains the optional prefix.
         *
         * @return this returns the prefix for this section
         */
        public String getPrefix() {
            return null;
        }

        /**
         * This is used to acquire the text label for this section if
         * one has been specified. A text label can only exist in a
         * section if there are no elements associated with the section
         * and the section is not composite, as in it does not contain
         * any further sections.
         *
         * @return this returns the text label for this section
         */
        public Label getText() {
            return null;
        }

        /**
         * Returns a <code>LabelMap</code> that contains the details for
         * all fields and methods marked with XML annotations. All of the
         * element annotations are considered and gathered by name in
         * this map. Also, if there is an associated <code>Style</code>
         * for serialization the element names are renamed with this.
         *
         * @return returns the elements associated with this section
         */
        public LabelMap getElements() {
            return new LabelMap(scanner);
        }

        /**
         * Returns a <code>LabelMap</code> that contains the details for
         * all fields and methods marked with XML annotations. All of the
         * attribute annotations are considered and gathered by name in
         * this map. Also, if there is an associated <code>Style</code>
         * for serialization the attribute names are renamed with this.
         *
         * @return returns the attributes associated with this section
         */
        public LabelMap getAttributes() {
            return new LabelMap(scanner);
        }

        /**
         * Returns the named element as a <code>Label</code> object.
         * For convenience this method is provided so that when iterating
         * over the names of the elements in the section a specific one
         * of interest can be acquired.
         *
         * @param name the name of the element that is to be acquired
         * @return this returns the label associated with the name
         */
        public Label getElement(String name) {
            return null;
        }

        /**
         * Returns the named section as a <code>Section</code> object.
         * For convenience this method is provided so that when iterating
         * over the names of the elements in the section a specific one
         * of interest can be acquired.
         *
         * @param name the name of the element that is to be acquired
         * @return this returns the section associated with the name
         */
        public Section getSection(String name) {
            return null;
        }

        /**
         * This is used to acquire the full element path for this
         * section. The element path is simply the fully qualified
         * path for this expression with the provided name appended.
         * If this is an empty path, the provided name is returned.
         *
         * @param name this is the name of the element to be used
         * @return a fully qualified path for the specified name
         */
        public String getPath(String name) {
            return null;
        }

        /**
         * This is used to acquire the full attribute path for this
         * section. The attribute path is simply the fully qualified
         * path for this expression with the provided name appended.
         * If this is an empty path, the provided name is returned.
         *
         * @param name this is the name of the attribute to be used
         * @return a fully qualified path for the specified name
         */
        public String getAttribute(String name) {
            return null;
        }

        /**
         * To differentiate between a section and an element this can be
         * used. When iterating over the elements within the section the
         * names of both elements and sections are provided. So in order
         * to determine how to interpret the structure this can be used.
         *
         * @param name this is the name of the element to be determined
         * @return this returns true if the name represents a section
         */
        public boolean isSection(String name) {
            return false;
        }
    }
}

